1 files changed, 67 insertions, 0 deletions
diff --git a/libslang/examples/utmp.sl b/libslang/examples/utmp.sl
new file mode 100644
index 0000000..b7a69af
--- /dev/null
+++ b/libslang/examples/utmp.sl
@@ -0,0 +1,67 @@
+% This file illustrates how to read a binary file into a structure.  In this
+% case, the file is the Unix utmp file.
+%
+% Note that the format of the utmp file will vary with the OS.  The format
+% encoded here is for glibc Linux, but even that may be version-dependent.
+
+variable format, size, fp, buf;
+
+variable is_glibc = 1;
+
+#ifeval is_glibc
+typedef struct
+{
+   ut_type, ut_pid, ut_line, ut_id,
+     ut_user, ut_host, ut_exit, ut_session, ut_tv, ut_addr
+} UTMP_Type;
+% The ut_tv is a timeval structure which has the format: l2
+% Also the ut_exit field is a struct of h2
+format = pad_pack_format ("h i S32 S4 S32 S256 h2 l l2 k4 x20");
+#else   
+typedef struct
+{
+   ut_type, ut_pid, ut_line, ut_id,
+     ut_time, ut_user, ut_host, ut_addr
+} UTMP_Type;
+format = pad_pack_format ("h i S12 S2 l S8 S16 l");
+#endif
+
+size = sizeof_pack (format);
+vmessage ("Sizeof of utmp line: %d bytes", size);
+
+define print_utmp (u)
+{
+   () = fprintf (stdout, "%-16s %-12s %-16s %s\n",
+		 u.ut_user, u.ut_line, u.ut_host,
+#ifeval is_glibc
+		 ctime (u.ut_tv[0])
+#else
+		 ctime (u.ut_time)
+#endif
+		 );
+}
+
+variable Utmp_File;
+foreach (["/var/run/utmp", "/var/log/utmp"])
+{
+   Utmp_File = ();
+   fp = fopen (Utmp_File, "rb");
+   if (fp != NULL)
+     break;
+}
+
+if (fp == NULL) error ("Unable to open utmp file");
+
+() = fprintf (stdout, "%-16s %-12s %-16s %s\n",
+	      "USER", "TTY", "FROM", "LOGIN@");
+
+variable U = @UTMP_Type;
+
+while (size == fread (&buf, Char_Type, size, fp))
+{
+   set_struct_fields (U, unpack (format, buf));
+   print_utmp (U);
+}
+
+() = fclose (fp);
+